Compositions for washing and cleaning hard nontextile surfaces in the household and commercial sector are generally intended to develop a small foam volume on use, which further reduces significantly within a few minutes. Compositions of this kind have been known for a long time and are established on the market. They essentially comprise aqueous surfactant solutions of different kinds with or without the addition of builders, solubilizers (hydrotropes) or solvents. At the beginning of cleaning work, the consumer does in fact desire a certain foaming of the application solution, for the purpose of demonstrating effectiveness, but the foam ought rapidly to collapse so that areas once cleaned need not be wiped again. For this purpose, the compositions-of the type mentioned are normally formulated with low-foaming nonionic surfactants.
For machine-washed kitchen- and tableware, more stringent requirements are nowadays imposed than for handwashed ware. For instance, even ware fully cleaned of its food residues is considered imperfect if, following machine washing, it still has whitish spots, originating from water hardness or other mineral salts, which derive from dried-on water droplets for lack of wetting agents. In order to obtain spotless ware with a clear luster, therefore, rinse aids are used. The addition of liquid or solid rinse aid, which may be added separately or may already be present in a ready-to-use presentation form together with the detergent and/or regenerating salt (xe2x80x9c2 in 1xe2x80x9d, xe2x80x9c3 in 1xe2x80x9d, e.g., in the form of tabs and powders), ensures that the water runs off as fully as possible from the ware so that at the end of the wash program the various surfaces are lustrous and free from residue.
Customary commercial rinse agents constitute mixtures of, for example, nonionic surfactants, solubilizers, organic acids and solvents, water and, where appropriate, preservatives and fragrances.
The function of the surfactants in these compositions is to influence the surface tension of water in such a way that it is able to run off in an extremely thin coherent film from the ware so that no water droplets, streaks or films remain in the subsequent drying process (the effect referred to as wetting).
Accordingly, surfactants in rinse aids are also required to suppress the foam which occurs as a result of food residues in the dishwasher. Since the rinse aids usually include acids for enhancing the dry-clear effect, the surfactants used must also be relatively hydrolysis-insensitive to acids. Rinse aids are used both in the household and in the commercial sector. In domestic dishwashers, the rinse aid is normally metered in after the prewash cycle and cleaning cycle at just 40xc2x0 C.-65xc2x0 C. The commercial dishwashers operate with only one wash liquor, which is refreshed only by addition of the rinse solution from the preceding wash. Throughout the entire wash program, therefore, the water is never completely replaced. Accordingly, the rinse aid must also have a foam suppressing effect, must be temperature-stable at a sharp temperature gradient of 85-35xc2x0 C., and must also be sufficiently stable toward alkali and active chlorine.
The German laid-open specification DE 19738866 describes surfactant mixtures comprising hydroxy mixed ethers and nonionic surfactants, such as fatty alcohol polyethylene glycol/polypropylene glycol ethers, where appropriate with endgroup capping, which exhibit very good foaming behavior and display outstanding rinse-clear effects in rinse agents.
From the German laid-open specification DT 2432757 it is known that hydroxy mixed ethers are used as foam suppressants in detergents and cleaning products.
It was an object of the present invention to develop detergents and cleaning products which combine good foaming and cleaning behavior, in particular a very good runoff behavior on plastic surfaces and high material compatibility of the surfaces to be cleaned. Furthermore, the intention was to provide hydroxy mixed ethers which can be incorporated with particular advantage into solid formulations.
The object has been achieved by developing hydroxy mixed ethers which, in addition to their foam suppressing effect, also exhibit a high level of compatibility for plastic. Surprisingly, the hydroxy mixed ethers of the invention are particularly notable for their colorless, clear appearance, which opens up the possibility of incorporation into a large number of detergents and cleaning products without a complicated bleaching operation.
The invention provides detergents and cleaning products containing hydroxy mixed ethers (HMEs) of the formula (I):
R1O[CH2CHR4O]x[CH2CHR3O]yCH2CH(OH)R2xe2x80x83xe2x80x83(I)
in which R1 stands for an alkyl and/or alkenyl radical having from 4 to 22 carbon atoms; R2 stands for an alkyl and/or alkenyl radical having from 2 to 22 carbon atoms; R4 stands for hydrogen or a methyl radical; R3 stands for hydrogen or a methyl radical; x is from 1 to 40; y is from 1 to 40; and x+y greater than =1, characterized in that the alkylene units [CH2CHR4O] and [CH2CHR3O] are in randomized form.
Preference is given to those hydroxy mixed ethers which contain the alkylene units [CH2CHR4O] and [CH2CHR3O], preferably ethylene oxide and propylene oxide, in xe2x80x9crandomizedxe2x80x9d form, i.e., the prior mixing of the alkoxylation reagents and reaction with the alcohol and subsequent epoxide closure produces hydroxy mixed ethers which possess a statistical, random distribution of the alkylene units. Particular preference is given to hydroxy mixed ethers containing ethylene oxide units and propylene oxide units randomized in a ratio of from 40:1 to 40:5.